1. Field of the Invention
The present invention relates to a sheet for forming an image provided with a mark which can identify information concerning the sheet for forming an image, for instance, manufacturers, distributors, product lines, availability of product, product forgery or the like (hereinafter referred as an “identifying mark”), an image forming method and an image forming apparatus using the sheet for forming an image.
2. Description of the Related Art
Conventionally, as an image forming method for making hard copies of images in forms of video images, digital photographs or the like, there is a thermal transfer recording method. In an image forming process using the thermal transfer recording method, an image is printed by transferring a colorant from a thermal transfer sheet to a thermal transfer image-receiving sheet using a thermal head mounted on a printer (image forming apparatus) so that a desired image is obtained.
In the thermal transfer recording method, generally printing is carried out by using a thermal transfer sheet having a combination of some colorant layers, for example, three primary colors of yellow, magenta and cyan, and if necessary, colorants of black or so called special colors (namely, specially prepared exclusive colors) such as a metallic color, a fluorescent color or the like in order to form a full color image such as a video image, a digital photograph or the like.
Normally, a thermal transfer sheet often comprises a long substrate film made of polymeric resin such as polyethylene terephthalate or the like and colorant layers comprising aforementioned colorants disposed thereon in a manner that the colorant layers are provided alternately (it is called “alternately provided side by side”) and repeatedly in a certain form and distance. For the purpose of protecting an image obtained by printing, the thermal transfer sheet may be provided with a thermally transferable protect layer adjacent to the colorant layer of the substrate. Other thermally transferable layers than the colorant layer and the protect layer may be formed on the thermal transfer sheet.
Moreover, an image may be formed by using a combination of plural kinds of monochrome thermal transfer sheets, each of which has a colorant layer of single color on the whole surface.
Generally, a size and a form per frame of a thermally transferable layer formed on a thermal transfer sheet are often determined in accordance with a thermal transfer image-receiving sheet used in combination with the thermal transfer sheet and a size and a form of a desired image.
A type of thermal transfer sheet used for one kind of printer is not always one type but it varies according to the size (for instance, postcard size, A5 or A4 size, or the like), presence of a protect layer, presence and sort of a special color, and sort of thermal transfer image-receiving sheet used in combination with the thermal transfer sheet.
Further, there are cases that plural distributors sell printers of same model under different product names, and equivalent thermal transfer sheets used for the printers may be given different product names by those distributors.
Therefore, in the case that a printer accepts various kinds of thermal transfer sheets, the identification of types of thermal transfer sheets is a substantive issue. Generally, a different printing mode for each type of thermal transfer sheet is set to a printer. If a wrong mode is selected, a predetermined printing performance and durability cannot be obtained. Moreover, there is even a possibility of causing a printer trouble or a malfunction in printing operation.
Conventionally, identification of type of a thermal transfer sheet is carried out in such a manner that an user confirms written type of a thermal transfer sheet, and then the user input the type in a printer or another printing controller such as a personal computer.
There is also known a method that a printer acknowledges an identification mark provided on a thermal transfer sheet, thereby the printer automatically identifies a type of the thermal transfer sheet and selects an appropriate setting (Japanese Patent Application Laid-open (JP-A) No. 2000-33781 and JP-A No. 2000-33782). In such a method using the identification mark, there is a case that a printer simultaneously confirms presence of a thermal transfer sheet.